Characterization of a novel nitrilase, BGC4, from Paraburkholderia graminis showing wide-spectrum substrate specificity, a potential versatile biocatalyst for the degradation of nitriles.

OBJECTIVE: To investigate the biodegradation of nitriles via the nitrilase-mediated pathway.

RESULTS: A novel nitrilase, BGC4, was identified from proteobacteria Paraburkholderia graminis CD41M and its potential for use in biodegradation of toxic nitriles in industrial effluents was studied. BGC4 was overexpressed in Escherichia coli BL21 (DE3), the recombinant protein was purified and its enzymatic properties analysed. Maximum activity of BGC4 nitrilase was at 30 °C and pH 7.6. BGC4 has a broad substrate activity towards aliphatic, heterocyclic, and aromatic nitriles, as well as arylacetonitriles. Iminodiacetonitrile, an aliphatic nitrile, was the optimal substrate but comparable activities were also observed with phenylacetonitrile and indole-3-acetonitrile. BGC4-expressing cells degraded industrial nitriles, such as acrylonitrile, adiponitrile, benzonitrile, mandelonitrile, and 3-cyanopyridine, showing good tolerance and conversion rates.

CONCLUSION: BGC4 nitrilase has wide-spectrum substrate specificity and is suitable for efficient biodegradation of toxic nitriles.